Patients undergoing diathermic deep-heating treatment occasionally experience superficial burning to the skin surrounding the area of intended treatment, similar to sunburn. As treatment areas are internal, the skin area in question intervenes between the treatment area and source of RF energy. In particular RF burning does not appear to be the cause, as the measured increase in temperature at the actual intended treatment site is not more than a few degrees Fahrenheit. These and other observations lead applicants to conclude that burning is caused by electrical energy capacitively coupled through the wire insulation, wherein the capacitance value in question is determined substantially by the dielectric constant of the insulation at the RF frequency used in diathermy. (possibly as well as extraneous factors like air gaps which should be controlled by the fit of the garment and so on)
It is evident from experience, that in the case of diathermy, magnetic heating inside the therapeutic device, or deep heating, causes an increase in temperature of a few degrees at most. However, for an entirely different reason, patients occasionally experience superficial burning, somewhat resembling a sunburn. This burning affects only a top layer of skin.
Solutions entailing better insulation for applicator wiring are to some extent feasible but are expensive, do not completely solve the problem because they still have some capacitive coupling, and do not provide the same benefit to manufacturing with respect to other desirable characteristics of the insulation, such as bend radius. To some extent burning can also be reduced by proper choice of fabric material and thickness, especially local burning caused by a single turn of the wire as contrasted by relatively low heat applied in the space between two turns.